Thirty years ago, Paul Knott broke his neck in a car accident, landing him in a wheelchair and ending his career as a firefighter with the California Department of Forestry and Fire Protection. Since then, he’s gone back to school, finished his degree, started working as a “data cowboy” (his words), trained people on dispatch systems (still for CAL FIRE), and raised three Australian shepherds.

He got his first dog, Bear, shortly before the accident, and ended up training him as a service dog to get around his landlords’ “no pets” policy. Bear and his successors—first Ed, now Charlie—have accompanied Knott everywhere: to work, on errands, around town. And he’s noticed that on their wanderings, Charlie draws in a lot of new friends.

“My guy is very eager to meet people,” says Knott, now 62 years old. “He’ll look ‘em right in the eye and say ‘Hi,’ so that starts the interaction, and the person starts conversing about the animal. ‘What’s his name? Oh, he's your helper?’ And within five or 10 minutes, you could be into a conversation that person would've never imagined initiating without the animal there.”

Though anyone who has found her hands itching to pet a stranger’s dog when it passes on the sidewalk looking all pettable knows this in her heart to be true, it’s nice to have the data to back it up: Dogs are great facilitators of social interaction. Especially between strangers.

In studies observing the reactions people get while out and about with dogs, researchers have found that strangers offer more smiles and friendly glances to people with dogs, and are more likely to approach and have a conversation with someone with a canine companion. In one study from 2008, people helped a stranger who dropped a handful of coins pick them up more often if he had a dog with him, and were more likely to give him money for the bus when he asked.

People typically treat strangers in public places with what the sociologist Erving Goffman termed “civil inattention.” They may acknowledge each other with brief glances, but they’ll look quickly away. The glancer is recognizing that the other person is there, but signaling that he himself doesn’t want to interact, and also being respectful of the fact that the other person probably doesn’t want to interact, either.

But dogs do not give a hoot about our elaborate, chilly social dances. They’ll interact with whomever they like, thanks very much. This helps break the barrier of civil inattention in two ways: One, if you see someone with a dog, and you like dogs, then you know you have something in common with that person, making them a little bit less of an unknown. And two, “it is as if the interactional openness of pet dogs … is highly contagious, infecting and transforming anyone who accompanies them in public into ‘open persons.’”

So wrote researchers in a 1991 paper in the Journal of Contemporary Ethnography in which one of the authors straight-up infiltrated a group of dog owners that hung out at his local park and took notes on their behavior as he slowly became their friend. He noticed that the dog owners were open to talking with other people in the park, and welcomed other dog owners (who weren’t part of their group) to let their dogs off the leash to play. But the conversations were pretty much entirely dog-centric, and at first the owners would even address a newcomer’s dog rather than the person.

On the author’s second visit to the park with his dog, Max, one of the women from the group came up to them. “She bent down and began petting Max,” he wrote. “She spoke to him in the tones a mother uses with her child: ‘You’re so cute! What a good boy. You’re so friendly, aren’t you? Yes, you are.’ She then directed a number of questions to me: ‘What’s his name? How old is he?’”

The term for what she’s doing is “triangling”—addressing the dog instead of the human in order to minimize the risk of talking with a stranger. The dog is a safer target; it probably won’t reject you. (I mean, it might wander away to pee or chase a squirrel.)

“It gives them a very safe target of conversation,” says Lynette Hart, a professor of veterinary medicine at the University of California, Davis. This is true of other animals as well—a study Hart did in 1992 found that people were more likely to approach a stranger sitting in a park with a turtle or a rabbit than if they were sitting there blowing bubbles or watching television.

“Any furry sweet animal has some attraction and sometimes there’s just the novelty effect of an unusual animal,” Hart says. “But there is something so amazing about dogs in their attentiveness to people, their willingness to solicit friendship. The species is so well suited to humans.”

But dogs aren’t only good icebreakers for the frozen walls of indifference that people build around themselves in public. They can also overcome the harsher reactions that people with disabilities get from strangers.

“Sometimes you go out in public and do your thing at the bank or the store, or whatever, and although everybody is polite, you can kind of see people looking out the side of their eye at you,” Knott says.

A few years after becoming a quadriplegic, Knott participated in a 1988 study done by one of Hart’s grad students, Jane Eddy. Eddy, Hart, and Ronald Boltz followed people in wheelchairs around in shopping centers and on the UC Davis campus, with and without dogs, and watched how people reacted to them. With the dogs present, people got many more smiles and conversations out of strangers, and strangers were less likely to deliberately avert their gaze from or walk out of their way to avoid the disabled person if he had a dog.

“It was just such a big normalizing effect,” Hart says.

Part of the reason that people are drawn to people with dogs is that humans just tend to think of animal owners more positively. In a study in which participants were asked to rate people in drawings on different attributes (unhealthy versus healthy, friendly versus hostile, intelligent versus unintelligent, etc.), they rated the cartoon people more positively when animals were included in the drawings.

This is something that many Tinder users intuitively understand, if the number of dogs in profile pictures is any indication. And it probably works—in the same 2008 study that included the coin-dropping test, a male researcher was able to get a lot more women’s phone numbers when he had a dog with him. He succeeded 9 percent of the time without the dog, and 28 percent of the time with the dog. (The dog, if you were wondering, was “evaluated [in a previous evaluation] as kind, dynamic, and pleasant.” Science!)

It’s an attitude that stems from the “fundamental attribution error,” says Alan Beck, a professor of animal ecology at Purdue University’s School of Veterinary Medicine. The fundamental attribution error is a social-psychological concept describing how people tend to think that what other people do is indicative of their personalities, without taking external factors into account.

“The classic [example] is: If I trip, the first thing I do is look down to see who the hell left something there, whereas if you trip, I call you a klutz,” Beck says. “Well I think when we see people with animals, we just assume that relationship is wonderful and it’s a reflection of that person. We assume they are literally the true good dog owner, as opposed to they just happen to be with a dog or maybe he hates the dog, or whatever … Hitler was a great dog lover.”

But as the ethnographers noticed during their undercover operation among the group of dog owners, spending time with a dog and its human will likely eventually give you some insight into that human’s moral character. When owners’ dogs got into trouble at the park, fighting with other dogs, or rolling around in the mud, how the owners handled it gave them a chance to “demonstrate their own commitment to the moral order that their dogs and by association they themselves, had transgressed,” the study reads.

Seeing someone with a dog offers you a chance to judge their character, perhaps falsely, but it also offers them a chance to prove themselves to you, and maybe, make a new friend. “Dogs, then, can provide more companionship for humans than merely their own company,” the ethnographers write.

Knott feels this as well. “I know this last time when I lost Ed, it was almost a year and a half or so before I got Charlie here to replace him, and you just don’t want to get out as much,” he says. “Certainly the dog makes you get out, get your exercise, just makes it more fun to get out in the world. People are all smiley. Think about it: If you had something with you that made everybody smile, wouldn’t you want to get out more and do more?”